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Worksheets7th Grade Science
Total questions: 95
Worksheet time: 1hrs 15mins
Which property is shared by most molecular compounds?
high boiling point
high melting point
low melting point
nonpolar bonds
When an atom loses an electron it becomes a _______ ___.
(a)
In a chemical formula for an ionic compound which item is written first?
the name of the positive ion
the name of the negative ion
the name of the electron
the name of the the charges
Magnesium bromide is an ionic compound with the chemical formula MgBr2, What does the "2" tell you?
Bromide has a 2-charge
There are two magnesium ions to every
bromide ion
There are two bromide ions for every
magnesium ion.
The chemical name for the compound with the formula Na2S is ______ _______.
(a)
What is a double bond?
a bond between two atoms
one pair of electrons shared between two atoms
two pairs of electrons shared between two atoms
three pairs of electrons shared between two atoms
Electrons involved in bonding between atoms are _______ _______.
(a)
A mixture made of two or more elements, at least one of which is metal is called an (a) .
What is it called when metal can be rolled into thin sheets, as in aluminum foil or beaten into complex shapes?
(a)
Which of the following groups contains the most reactive elements?
Alkali Metals
Alkali Earth Metals
Hallogens
Noble Gases
Which of the following is a property of ionic compounds?
low melting points
low boiling points
form hard, brittle crystals
no charged particles
An ionic bond is the attraction between...
similarly charged ions
oppositely charged ions
neutral ions
neutral atoms
Ions that are made of more than one atom are examples of ________ ___.
(a)
A chemical bond formed when two atoms share electrons is called a _______ _____.
(a)
The principle of conservation of mass is true
only in open systems
only in closed systems
in both open and closed systems
In chemical reactions, what does the principle of conservation of mass tell you?
matter is not created or destroyed
the total mass of reactants is greater than the mass of products
matter is not changed
Chemicals that act as biological catalysts by speeding up reactions in living things are called (a) .
Which of the following best describes a metal crystal?
metal atoms held together by covalent bonds
metal atoms held together by ionic bonds
positive metal ions surrounded by freely moving valence electrons
neutral metal ions surrounded by freely moving valence electrons
Ionic compounds are electrically (a) .
Chemistry is
a characteristic of a substance that can be observed without changing it into another substance
the study of matter and how it changes
anything that has mass and takes up space
a rapid reaction called between oxygen and a substance called a fuel
The only sure evidence for a chemical reaction is
the formation of a gas
a color change
the production of one or more new substances
changes in properties
A material used to decrease the rate of the chemical reaction is a(n)
(a)
CaCO3 represents a chemical
(a)
Which is the correct chemical equation for the following statement? Sodium reacts with oxygen in a 2 to 1 ratio to produce sodium oxide.
4 Na + O2-->2 Na2O
2 Na + O2--> 2 NaO
Na2O + O2--> 2 NaO
Na2 + O2--> Na2O2
Which of the following is an example of how to supply activation energy to begin a reaction?
Cool the reaction flask in an ice bath
add a catalyst
heat the reaction flask on a hot plate
add an inhibitor
A bottle of hydrogen peroxide that eventually turns into a bottle of water and oxygen gas is an example of a
synthesis reaction
decomposition reaction
a replacement reaction
precipitate reaction
What type of reaction is FeS + 2 HCL--> FeCl2 + H2S?
a synthesis reaction
a decomposition reaction
a single replacement reaction
a double replacement reaction
What happens when chemical bonds break and new bonds form?
a physical change
a chemical change
matter is destroyed
surface area increases
A shorter, easier, way to show a chemical reaction, using symbols instead of words, is called a
chemical equation
chemical formula
symbol
subscript
The substances liosted on the left side of a chemical equation are the
products
coefficients
precipitates
reactants
Which two processes could be considered opposites?
a decomposition reaction and a single replacement reaction
a single replacement reaction and a double replacement
a precipitate reaction and a synthesis reaction
a synthesis reaction and a decomposition
A chemical reaction that absorbs energy in the form of heat is described as
(a)
The minimum amount of energy needed to start a reaction is the
exothermic energy
endothermic energy
activation energy
chemical energy
When a chemical reaction takes place in an open system,
matter can enter from or escape to the surroundings
matter is not allowed to enter from or escape to the surroundings
matter can enter from the surroundings, but cannot escape to the surroundings
matter cannot move at all
Every chemical reaction involves a change in
(a)
In Ernest Rutherford's gold foil experiment, most positively charged particles passed through the foil, but few particles were deflected strongly. This result caused Rutherford to infer
that electrons move in orbits around the nucleus of an atom
that an atom's positive charge mustr be clustered in a tiny region in its center
that electrons have almost no mass
that an atom consists of negative charges scattered in a ball of positive charge
Mendeleev created the first periodic table by arranging elements in order of
decreasing atomic mass
increasing atomic mass
increasing atomic number
increasing melting points and densities
The atomic number of an element is based on the
mass of its nucleus
number of electrons around its core
number of protons in its nucleus
number of neutrons in its nucleus
From an element's location in the periodic table, you can predict
its properties
its chemical name
its chemical symbol
when it was discovered
In general, which of the following statements about metals is true?
Metals need to be stored in sealed containers for safety.
Metals are malleable, ductile, and can carry an electric current.
Metals are highly reactive substances.
Metals do not react with oxygen.
The two most common alkaline earth metals are
copper and zinc
iron and silver
sodium and potassium
calcium and magnesium
At room temperature, more that half of the nonmetal elements are
(a)
The elements that do not ordinarily form compounds are
(a)
Beta radiation consists of particles that are identical to
(a)
Measurements of half-life make radioactive isotopes useful for
radiation therapy
tracing oil spills
building shields to absorb nuclear radiation
determining the ages of rocks and fossils
Which of these statements about a column of the periodic table is true?
The elements have a similar characteristics.
The elements have a wide range of characteristiucs.
The elements have the same atomic number.
The elements have the same mass.
In the periodic table, the most reactive metals are found
in Group 1, the first column on the left.
in Period 1, the first row across the top.
in Group 13 through 16 in the center.
in Periods 6 and 7 at the bottom.
Which group contains the most elements?
(a)
A material is said to be ductile if it
can be pulled out,or drawn, into a long wire.
can be hammered or rolled into flat sheets and other shapes.
can be transfer heat or electricity to another material.
is a mixture of a metal with at least one other element.
In an atom, the number of protons equals the number of
(a)
The elements in a row of the periodic table
are in the same family.
have the same or nearly the same properties.
have the same average atomic mass.
have properties that change in a pattern.
What information in the periodic table indicates the number of protons in an atom?
the position of the element in its column
the element's chemical symbol
the element's atomic number
the element's atomic mass
Which parts of the atom move around the nucleus?
(a)
Which group of elements have some properties of metals and some properties of nonmetals?
(a)
What particles in atoms have negative charge?
(a)
Fluorine, chlorine,bromine, and iodine are part of a family called
(a)
The atomic nuclei of unstable isotopes release fast-moving particles and energy in a process called
radioactive decay
radioactive dating
radioactive waste
radioactive tracers
The half-life of a radioactive isotope is the length of time needed for half the atoms of a sample to
(a)
Radioactive isotopes called (a) can be used to detect some medical problems.
A piece of paper will provide protection from
(a)
Orderly crystal shapes, high melting points, and electrical conductivity when dissolved in water are properties of (a) compounds
When electrons are (a) between two atoms, a covalent bond is formed.
A low melting point is one property of (a) compounds.
(a) changes occur when existing bonds break and new bonds form.
The amount of matter in a chemical reaction (a) .
(a) is the process of making a more complex compound from simpler substances.
A chemical reaction may be detecyted by observing changes in the (a) of matter.
The series of electron orbits in (a) model resemble planets orbiting the sun or the layers of an onion.
The modern periodic table is organized according to (a) .
The horizontal rows in the periodic table are known as (a) .
Ionic compounds that dissolve in water conduct electricity because they break into (a) that move freely.
When ions having a positive charge form bonds with ions having a negative charge, the charge on the resulting compind is (a)
Bonds that form between two nonmetal atoms usually are (a) bonds.
Solid metals are good conductors of heat and (a) .
Molecular compounds that dissolve in water do not conduct electricity becasuse no (a) are present.
Because the electrons in a molecule of hydrogen fluoride(HF) are more strongly pulled toward the fluorine atom, the molecule is (a) .
A metal crystal consists of positively charged metal ions embedded in a sea of freely moving (a) .
The (a) is the amount of one material present in a given volume of another material.
In a (a) change, elements and/or compounds rearrange to form new substances.
(a) changes occur when bonds form between atoms, or when bonds break and new bonds form.
The law of (a) states that during a chemical reaction, matter is not created or destroyed.
A burning match is an example of an (a) where matter can enter from or escape tp the surroundings.
The process of solid ice changing into liquid water is a (a) change.
The (a) of a compound shows the ratio of elements present in the compound.
A material used to decrease the rate of a reaction is called (a) .
Scientific theories often make use of (a) , which are representations of an idea to help scientists understand what they cannot observe directly.
The spontaneous emission of radiation by an unstable atomic nucleus was named (a) by Marie Curie.
Mendeleev discovered that periodic patterns appeared when he arranged the elements in order of increasing (a) .
The property of an element that indicates the number of protons in its atoms is the (a) .
The chemical reactivity of metals tends to (a) from left to right across the periodic table.
Most metals are in the (a) state at room temperature.
The (a) is the very small center of an atom.
Elements known as (a) are located to the right of the metalloids on the periodic table.
At room temperature, all metalloids are solids, while many nonmetals are (a) .
Because radioactive isotopes decay at a predictable rate, the half-life can be used to tell how old a material is by the process of (a) .
